https://github.com/rubenwardy/rubix_kernel

A simple kernel for ARMv7
https://github.com/rubenwardy/rubix_kernel

filesystem kernel posix

Last synced: 2 months ago
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A simple kernel for ARMv7

• Host: GitHub
• URL: https://github.com/rubenwardy/rubix_kernel
• Owner: rubenwardy
• Created: 2017-03-13T16:22:10.000Z (about 8 years ago)
• Default Branch: master
• Last Pushed: 2018-06-06T22:37:25.000Z (almost 7 years ago)
• Last Synced: 2025-02-28T10:09:18.505Z (3 months ago)
• Topics: filesystem, kernel, posix
• Language: C
• Homepage: https://blog.rubenwardy.com/2018/04/05/simple-kernel-in-c/
• Size: 285 KB
• Stars: 6
• Watchers: 2
• Forks: 0
• Open Issues: 2
• Metadata Files:
  • Readme: README.md

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README

        
# Rubix OS

## Features

* SYS Calls

	* `yield` - ends the current time slice.

	* `write` - writes to an open file descriptor.

	* `read`  - reads from an file descriptor. Returns length of read, 0 on EOF.

	            May blocking - see `set_nonblocking`.

	* `close` - closes a file descriptor.

	* `dup2`  - duplicates fd from `old` to `new`. `new` is closed if it already exists.

	* `pipe`  - creates a pipe. fd[0] is read, fd[1] is write.

	* `fopen` - open file. Not quite POSIX, as it's non-blocking

	* `fork`  - clones process.

	            Return value is 0 if child, PID of child if parent, -1 if error.

	* `exec`  - replaces the process with another program. PID is kept.

	            Stack and FDs (except in/out/err) are destroyed.

	* `exit`  - exits with exit code.

	* `wait`  - waits for a child program to exit, and gives exit code.

	* `kill`  - sends a kill signal to a process. Killed processes will not return an exit code.

	            `signal` is not yet implemented.

	* `setpriority` - set priority of child process.

	* `set_nonblocking` - is not POSIX, unfortunately. Set pipe non-blocking.

* LibC help functions

	* `popen` - opens a process and returns a FD. Uses `fork`, `pipe`, `exec`, and `dup2`.

	* `wait`/`waitpid` - both use the `wait` syscall.

* Processe

	* **time slicing**      - timer based timer slices.

	* **priority-based**    - priority(P) = priority_base(P) + slices_since_last_ran(P)

	* **blocked queue**     - for processes waiting for a process or file resource.

	* **process ownership** - processes have a parent, which can kill/wait them.

	* **process groups**    - a limited type of process group, where all processes

	                          that share a parent and the parent itself are in a group.

* Files

	* `FiDes` - File descriptor. Interacted with using function pointers. Can be blocking or not.

	* `pipe`  - Pointed to by a FD.

	* `in/out/err` - these are "files" too!

	* `filesystem` - Files are limited to 256 bytes, maximum of 10 files.

## References

All references access March 2017.

### Online

* [Linux Man-pages](http://man7.org/linux/man-pages/). Various. man7.org

* [Wait sys call](http://pubs.opengroup.org/onlinepubs/000095399/functions/waitpid.html). The Open Group. pubs.opengroup.org

* [Exit sys call](http://pubs.opengroup.org/onlinepubs/000095399/functions/exit.html). The Open Group. pubs.opengroup.org

* [POSIX IPC](https://docs.oracle.com/cd/E19455-01/806-4750/6jdqdfltf/index.html). Oracle. docs.oracle.com

* [Linux Interprocess Communications](http://tldp.org/LDP/lpg/node7.html). Goldt. S, Van der Meer. S, Welsh. M. tldp.org

* [Interprocess Communication (IPC), Pipes](https://users.cs.cf.ac.uk/Dave.Marshall/C/node23.html). Marshall, D. Users.cs.cf.ac.uk

* [General overview of the Linux file system](http://www.tldp.org/LDP/intro-linux/html/sect_03_01.html). Machtelt. G. tldp.org

### Print

* Cormen. T, Leiserson. C, Rivest. R, Stein. C. *Introduction to Algorithms 3rd Edition*,  (Massachusetts Institute of Technology, 2009) Heapsort and Priority Queues. pp151-166